Explanation/Reference:
A: Traffic shaping and policing can work in tandem. For example, a good traffic shaping scheme should make it easy for nodes inside the network to detect misbehaving flows. This activity is sometimes called policing the traffic of the flow.
C: The simplest way to classify a packet is to use behavior aggregate (BA) classification.
For a specified interface, you can configure both a multifield classifier and a BA classifier without conflicts.
Because the classifiers are always applied in sequential order, the BA classifier followed by the multifield classifier, any BA classification result is overridden by a multifield classifier if they conflict.
References: http://www.juniper.net/techpubs/en_US/junos15.1/topics/concept/classifier-ba-overview-cos- config-guide.html